Endless Pampering Only For You - Chapter 19

Silas Blackwood wakes up with a machine in his chest – his missing mother's parting gift to help him survive the war with the Fae. This “system” grants him bizarre abilities: neuromancy (magic of the mind), biomancy (magic of the body), and essomancy (magic of souls and essences). Oh, and it fused a leviathan's mana core into his body. Because why not become part sea monster?At Arcanium University, a military boot camp churning out mage knights, Silas finds himself targeted by rich brats who think being born with a silver wand up their ass makes them special. When they leave him for dead, Silas decides it's time to show these spoiled kids what real power looks like.As Silas grows stronger, he discovers he can upgrade himself by absorbing essences from magical beasts and demons. Just when he thinks he's got a handle on things, Silas learns his mother's alive, and now he's got a new mission: a rescue that'll take him and his friends straight into the depths of Hell.

A skilled but unfortunate modern-day assassin was killed in a freak accident. However, he soon found himself summoned to another world by an evil wizard, who had him possess the body of a boy as an experiment. After successfully planning the evil wizard’s downfall, he used the wizard’s body as a springboard to gain influence and power in his new world.

- Description from Novelupdates

In the year 54 of the Konoha Calendar, two super geniuses appeared in the Konoha. One is named Uchiha Itachi, and the other is named Akihara Kagura. One is a tool of the village, willing to sacrifice everything for Konoha, except for his brother Uchiha Sasuke; the other claims to be a tool of the village, also willing to sacrifice everything for Konoha, including Uchiha Itachi's brother, Uchiha Sasuke.